The present invention relates to a longitudinal folding apparatus for webs on a folder of a rotary press, having a variable-position folding former.
DE 196 02 248 A1 discloses a longitudinal folding apparatus of a rotary press, having a folding former which is arranged behind a former roll and ahead of folding rolls in the web running direction. The folding former can be adjusted in parallel in the axial direction of the folding rolls. For this purpose, it is attached in a hinged fashion to thee threaded spindles which are mounted in the frame. The adjustment is carried out by rotation of the threaded spindles which are synchronized by means of a chain drive. The former roll is mounted in the frame. A round body ensures that the web is fed in the plane which includes the web bearing face of the folding former.
It is a disadvantage of this apparatus that the adjusting apparatus for the folding former is expensive. Moreover, the lowermost web can slip on the round body as a consequence of friction or the print can smear with the consequence of quality losses for the printed product.